Work vehicle

ABSTRACT

A work vehicle according to the present invention includes left and right axle cases of a rigid axle type, and left and right suspension mechanisms movable in the up-down direction relative to body frames and separately supporting the left and right axle cases, respectively. The work vehicle also includes (i) a first projection projecting downward from the left or right one of the body frames, (ii) a second projection projecting upward from that position on either the left and right axle cases or a frame body integrated with the axle cases which is opposite to the first projection in the left-right direction, and (iii) a lateral rod having a first end connected with the first projection and a second end connected with the second projection.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No.2019-171941 filed Sep. 20, 2019, the disclosure of which is herebyincorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a work vehicle including left and rightaxle cases of a rigid axle type, the left and right axle cases coaxiallysupporting left and right axles for driving left and right wheels,respectively.

BACKGROUND ART

An example work vehicle configured as above is disclosed in JP2009-67082 A. JP 2009-67082 A describes a rigid axle suspension forsuspending left and right wheels, the rigid axle suspension including(i) a pair of left and right arms for positioning the left and rightwheels in the front-rear direction, (ii) a pair of left and right coilsprings and a pair of left and right dampers for absorbing shock from aroad surface, and (iii) a lateral rod for positioning the left and rightwheels in the left-right direction.

The work vehicle disclosed in JP 2009-67082 A further includes (i) abody frame having a rear end portion supporting a pair of left and rightarms at an upper position and a pair of left and right arms at a lowerposition in such a manner that each pair of left and right arms areswingable on the core of a lateral shaft, (ii) an auxiliary frameconnected with the pair of left and right arms, the auxiliary framesupporting left and right rear axle cases, and (iii) coil springs anddampers connected with each other in such a manner as to reduce up-downmovement of the auxiliary frame. The lateral rod is, in particular,oriented laterally by (i) connecting a first end thereof with the bodyframe (“base frame” in the patent literature) and (ii) connecting asecond end thereof with the auxiliary frame.

SUMMARY OF INVENTION Technical Problem

The work vehicle disclosed in JP 2009-67082 A is configured such thatthe lateral rod has a first end connected with a bracket provided forthe body frame and a second end connected with a bracket provided forthe auxiliary frame.

A lateral rod receives a strong lateral force for positioning left andright wheels in the lateral direction relative to the body frame. Thebrackets disclosed in JP 2009-67082 A each need to have a greatstrength.

While an off-road multipurpose work vehicle is running, its wheels oftenbecome moved up and down greatly. Even for a work vehicle includingcoils and dampers as disclosed in JP 2009-67082 A, the wheels can reachtheir mechanical limits if lifted suddenly and greatly.

A work vehicle including wheels that can reach their mechanical limitsif lifted suddenly and greatly as described above will unfortunately letthe driver feel the shock, and thus has room for improvement. Further,the use of brackets, for example, for supporting a lateral rod involvesan increase in the number of parts used and structural complexity.

This has led to a demand for a work vehicle that allows a lateral rod tobe supported without an increase in the number of parts used and thatregulates lateral displacement of left and right wheels.

Solution to Problem

A work vehicle according to the present invention comprises: a leftwheel provided for a vehicle body; a right wheel provided for thevehicle body; a body frame provided for the vehicle body; a left axleconnected with the left wheel; a right axle connected with the rightwheel; a left axle case and a right axle case, the left and right axlecases being of a rigid axle type and supporting the left and right axlesso that the left and right axles are coaxial with respect to each other;a left suspension mechanism via which the body frame supports the leftaxle case; a right suspension mechanism via which the body framesupports the right axle case; a first projection projecting downwardfrom a left or right portion of the body frame; a second projectionprojecting upward from that position on either (i) the left and rightaxle cases or (ii) a frame body integrated with the left and right axlecases which is opposite to the first projection in a left-rightdirection; and a lateral rod having a first end connected with the firstprojection and a second end connected with the second projection.

With the above configuration, the lateral rod has (i) a first endconnected with a first projection projecting downward from the bodyframe and (ii) a second end connected with a second projectionprojecting upward from that position on either the axle cases or theframe body which is opposite to the first projection in the left-rightdirection. The above configuration thus allows a lateral rod to beprovided without use of brackets. The first projection is present on thebody frame, whereas the second projection is present on either an axlecase or the frame body. Placing a lateral rod between the first andsecond projections allows the body frame and left and right wheels to bepositioned in the left-right direction.

In particular, if the work vehicle has received an external force thatacts in such a manner as to laterally displace the axle cases, thesecond projection on an axle case allows the force to be transmittedfrom the lateral rod directly to the axle cases, thereby achieving astrong regulation.

With the above configuration, the work vehicle allows a lateral rod tobe supported without an increase in the number of parts used andregulates lateral displacement of left and right wheels.

The work vehicle may further comprise a first opposing portion at thatportion of either the left and right axle cases or the frame body whichis located below the first projection; a first buffer member on either alower surface of the first projection or the first opposing portion; asecond opposing portion at that portion of the body frame which islocated above the second projection; and a second buffer member oneither an upper surface of the second projection or the second opposingportion.

With the above configuration, if the wheels have become lifted greatly,the first buffer member (which is present between the first projectionand the first opposing portion) and the second buffer member (which ispresent between the second projection and the second opposing portion)prevent the wheels from disadvantageously reaching their mechanicallimits and absorb the shock at the same time. Further, the firstprojection and the second projection, each of which has a greatstrength, rigidly support the lateral rod and thereby strongly regulatelateral displacement of left and right wheels.

With the above configuration, the first projection and the secondprojection overlap with the axle cases in a plan view. Thus, if thewheels have become lifted greatly, the force caused by the axle casesbeing lifted can be received by the buffer members located at suchpositions that the force is linearly applied to the buffer members,thereby allowing the force to be reliably received with a greatstrength.

The work vehicle may further be configured such that the first opposingportion is an upper surface of the frame body; the first buffer memberis present on the lower surface of the first projection; the secondopposing portion is a lower surface of a bar-shaped member projectingdownward from the body frame; and the second buffer member is present onthe second opposing portion.

With the above configuration, if the wheels have become lifted greatly,the first buffer member on the lower surface of the first projectioncomes into contact with the upper surface of the frame body, while thesecond buffer member on the lower surface of the bar-shaped member comesinto contact with the upper surface of the second projection.

The above configuration allows the first buffer member and the secondbuffer member to be separated from the ground in the upward direction.The above configuration thus prevents muddy water and dust from adheringto and thereby degrading the first buffer member and the second buffermember in the case where the first buffer member and the second buffermember are each made of a rubber, for example.

The work vehicle may further be configured such that the first buffermember and the second buffer member are present at respective heightsthat are asymmetrical to each other in the left-right direction withrespect to a center of the vehicle body as viewed in a front-reardirection.

For instance, with the lower end of the first projection being lower inposition than the upper end of the second projection, while the firstbuffer member and the second buffer member are present at respectiveheights that are asymmetrical to each other with respect to the centerof the vehicle body, the lateral rod can be oriented substantiallyhorizontally as viewed in the front-rear direction. Orienting thelateral rod horizontally as such allows the lateral rod to receive forcein a compressing direction and a tensile direction along itslongitudinal direction. If an external force is applied that acts insuch a manner as to laterally displace the left and right rear wheels,the lateral rod regulates the displacement strongly.

The work vehicle may further be configured such that the left and rightwheels are rear wheels provided at a rear portion of the vehicle body.

With the above configuration, the lateral rod allows the body frame andthe left and right rear wheels to be positioned in the left-rightdirection even for a work vehicle in which the respective axles of therear wheels are supported respectively by the left and right axle casesof a rigid axle type.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of a work vehicle.

FIG. 2 is a side view of a motor part and a structure for suspendingrear wheels.

FIG. 3 is a rear view, illustrating how a lateral rod is placed.

FIG. 4 is a schematic plan view of a motor part and a structure forsuspending rear wheels.

FIG. 5 is a perspective view, illustrating a structure for supporting alateral rod.

DESCRIPTION OF EMBODIMENTS

The description below deals with an embodiment of the present inventionwith reference to drawings.

Overall Configuration

FIG. 1 illustrates a work vehicle including (i) a vehicle body 1, (ii) apair of left and right front wheels 2 provided at a front portion of thevehicle body 1, (iii) a pair of left and right rear wheels 3 at a rearportion of the vehicle body 1, (iv) a driving part A at a centralportion of the vehicle body 1, (v) a truck box 4 at a rear portion ofthe vehicle body 1, and (vi) a motor part B under the truck box 4.

The work vehicle is a four-wheel drive vehicle (in which the motor partB transmits a driving force to both the front wheels 2 and the rearwheels 3). The work vehicle is a utility vehicle designed to be used formultiple purposes such as farmwork and transportation. The truck box 4is configured such that a front portion thereof can be lifted for aslanted position in response to an operation of a dump cylinder (notshown in the drawings) to allow a load to be dumped rearward by its selfweight.

The driving part A includes (i) a driver's seat 5 for a driver to siton, (ii) a steering wheel 6 provided in front of the driver's seat 5 toallow the driver to steer the front wheels 2, and (iii) a floor 7 at alower portion.

The driving part A also includes ROPS frames 8 at left and rightpositions to protect the driver and any occupant in the event of aroll-over accident of the work vehicle. The driving part A also includesan occupant's seat (not shown in the drawings) provided at a left orright portion of the vehicle body and adjacent laterally to the driver'sseat 5.

[Vehicle Body]

As illustrated in FIGS. 1 to 3, the vehicle body 1 includes (i) a pairof left and right body frames 11 each in a region extending from aposition at a front portion of the driving part A through a space underthe floor 7 to the motor part B and (ii) left and right link frames 12provided for the motor part B in such a manner as to be verticallydisplaceable relative to the body frames 11.

The left and right body frames 11 each include a square pipe member. Thebody frames 11 each include (i) a front frame 11 a extending in thefront-rear direction below the floor 7, (ii) an intermediate frame 11 bextending obliquely rearward and upward from a position at a rearportion of the front frame 11 a, and (iii) a rear frame 11 c extendingrearward from a position at a rear portion of the intermediate frame 11b to be oriented horizontally under the truck box 4.

As illustrated in FIGS. 2 and 4, the work vehicle includes a unit frame13 (which is an example frame body) below the rear frames 11 c. The unitframe 13 is in the shape of a plate with a width slightly smaller thanthe left-right distance between the left and right rear frames 11 c. Asillustrated in FIG. 2, the left and right link frames 12 each include apair of upper and lower link members 12 a each in the form of a roundpipe member. The left and right intermediate frames 11 b have respectivelower portions to which a front bracket 14 is fixed. The unit frame 13has left and right portions to which a rear bracket 15 is fixed.

The pair of upper and lower link members 12 a each have (i) a front endlinked swingably to the front bracket 14 by a lateral shaft and (ii) arear end linked swingably to the rear bracket 15 by a lateral shaft.With this configuration, an external force applied to the unit frame 13causes the link frames 12 to swing and thereby causes the unit frame 13to move up and down relative to the body frames 11. In particular, theleft and right link frames 12 being swingable independently of eachother allows the unit frame 13 to become slanted in the left-rightdirection as well.

[Motor Part/Suspension Structure]

As illustrated in FIGS. 2 to 4, the motor part B is a unitized wholethat is made up of an engine 17, a continuously variable transmissiondevice 18, and a transmission case 19 connected with one another andthat is supported by the unit frame 13.

As illustrated in FIG. 4, the engine 17 is connected with a left sidesurface of a front end of the transmission case 19, whereas thecontinuously variable transmission device 18 is connected with a rightside surface of the front end of the transmission case 19. Thetransmission case 19 has a rear end portion with which axle cases 20 areconnected in such a manner as to project in the left-right direction.The axle cases 20 each contain a rear axle 21 extending therethrough.The rear axles 21 each have an outer end with which one of the rearwheels 3 is connected. Further, the motor part B includes a front-wheeldrive shaft 22 extending forward from the transmission case 19 andconfigured to transmit a driving force to the front wheels 2.

As illustrated in FIG. 4, the unit frame 13 has a rear end provided witha muffler 23 configured to reduce the discharge noise of the engine 17.The transmission case 19 contains (i) a gear shift part configured tochange the speed at which the rear wheels 3 are driven and (ii) adifferential gear configured to transmit a driving force to the left andright rear axles 21. The motor part B includes brake units provided nearthe respective outer ends of the left and right rear axles 21 to eachapply a braking force to the corresponding one of the rear wheels 3.

The above configuration allows a driving force of the engine 17 to be(i) transmitted to the transmission case 19 while being variednon-stepwise by the continuously variable transmission device 18 andthen (ii) transmitted from the transmission case 19 to the left andright rear wheels 3 and the left and right front wheels 2. This in turnallows the work vehicle to travel at a desired speed.

The work vehicle is configured such that the left and right rear axles21 are coaxial with respect to each other and that the left and rightaxle cases 20 are of the rigid axle type to maintain the coaxialrelationship. As illustrated in FIGS. 2 and 4, the left and right axlecases 20 are each fixed to the upper surface of the unit frame 13 withuse of a holder 25, so that the axle cases 20 and the unit frame 13 areintegrated with each other. The left and right holders 25 are eachprovided with an axle-side support 26. The rear frames 11 c each have alower surface provided with a frame-side support 27. The motor part Bincludes a suspension mechanism 28 between the axle-side support 26 andthe frame-side support 27. The suspension mechanisms 28 each include asuspension spring 28 a and a damper 28 b. The left and right suspensionmechanisms 28 each separately support the corresponding one of the leftand right axle cases 20.

With the left and right rear wheels 3 suspended with use of the left andright link frames 12 and the left and right suspension mechanisms 28 asdescribed above, the following advantage is achieved: Suppose that whenthe work vehicle is running, one of the left and right rear wheels 3 hasbeen lifted greatly as in the case where, for instance, one of the rearwheels 3 moves over a clod. In such cases, (i) the corresponding one ofthe suspension mechanisms 28 is compressed greatly, and (ii) the leftand right link frames 12 are swung independently of each other, causingthe unit frame 13 to be slanted in such a manner as to maintain thecoaxial relationship between the left and right rear axles 21.

As illustrated in FIGS. 2 to 5, the left and right rear frames 11 c haverespective rear ends connected with each other with use of a lateralreinforcing frame 29. The left rear frame 11 c has a lower surfacerearward of the corresponding axle case 20, the lower surface beingprovided with a left support 31 (which is an example first projection)projecting downward. The left support 31 has a lower surface providedwith a first buffer member 31 a made of a rubber. Further, the unitframe 13 has a left opposing portion S1 (which is an example firstopposing portion) immediately below the first buffer member 31 a. Thefirst buffer member 31 a has a lower surface separated from the leftopposing portion S1 by a gap.

The right rear frame 11 c has a lower surface rearward of thecorresponding axle case 20, the lower surface being provided with aright support 32 (which is an example bar-shaped member) projectingdownward. The right support 32 has a lower surface provided with a rightopposing portion S2 (which is an example second opposing portion). Theright opposing portion S2 is provided with a second buffer member 32 amade of a rubber.

The unit frame 13 has an upper surface immediately below the rightsupport 32, the upper surface being provided with a regulating body 33(which is an example second projection) standing thereon. The regulatingbody 33 has an upper surface provided with a flat regulating wall 33 a.The second buffer member 32 a has a lower surface separated from theregulating wall 33 a (which is on the upper surface of the regulatingbody 33) by a gap.

As illustrated in FIG. 3, the right support 32 projects downward by alength smaller than the length by which the left support 31 projectsdownward. This structure results in the first buffer member 31 a and thesecond buffer member 32 a being present at respective heights that areasymmetrical to each other in the left-right direction with respect tothe center of the vehicle body 1 as viewed in the front-rear direction.The above structure also allows the first buffer member 31 a and thesecond buffer member 32 a to be separated from the ground in the upwarddirection. This prevents muddy water and dust from adhering to andthereby degrading the first buffer member 31 a and the second buffermember 32 a.

As illustrated in FIG. 3, the lower surface of the first buffer member31 a is separated from the left opposing portion S1 by a distance equalto the distance by which the lower surface of the second buffer member32 a is separated from the regulating wall 33 a. This allows the firstbuffer member 31 a and the second buffer member 32 a to be compressedsimultaneously if the left and right rear wheels 3 have become liftedequally greatly. The first buffer member 31 a and the second buffermember 32 a may each be made of a flexibly deformable resin instead of arubber. The first buffer member 31 a and the second buffer member 32 amay also each be combined with a compression spring.

As illustrated in FIG. 5, the left support 31 (which is an example firstprojection) is a plate member bent to have a U-shaped cross section andthereby have a front wall and a rear wall. The plate member has an upperend welded or otherwise fixed to the left rear frame 11 c and thereinforcing frame 29. This allows the left support 31 to projectdownward from a bottom portion of the rear frame 11 c.

The right support 32 (which is an example bar-shaped member) includesmembers such as a square pipe member and rib members. The right support32 has an upper end welded or otherwise fixed to the lower surface ofthe right rear frame 11 c. This allows the right support 32 to projectdownward. The regulating body 33 (which is an example second projection)is a plate member bent to have a U-shaped cross section and thereby havea front wall and a rear wall. The plate member has a lower end welded orotherwise fixed to the upper surface of the unit frame 13. This allowsthe regulating body 33 to project upward from the upper surface of theunit frame 13.

As illustrated in FIGS. 2 to 5, the work vehicle includes a lateral rod35 between the left support 31 (which is an example first projection)and the regulating body 33 (which is an example second projection) forregulating displacement of the left and right rear wheels 3 in theleft-right direction with respect to the body frames 11. While a lateralrod is also referred to as a panhard rod, the description of the presentembodiment consistently uses the term “lateral rod” throughout.

The lateral rod 35 has opposite ends each having a ring-shaped holdingpart 35 a. The lateral rod 35 is held in position by (i) placing one ofthe holding parts 35 a between the front wall and the rear wall of theleft support 31, (ii) placing the other holding part 35 a between thefront wall and the rear wall of the regulating body 33, and (iii)fastening each holding part 35 a with a connecting bolt 36.

The left support 31 and the regulating body 33, which determine thelimit on how much the rear wheels 3 can be lifted, double as members forsupporting the lateral rod 35. This eliminates the need to additionallyprovide brackets for supporting the lateral rod 35. The above simplestructure makes it possible to avoid an increase in the number of partsused and thereby avoid structural complexity, while allowing the lateralrod 35 to strongly regulate displacement of the left and right rearwheels 3 in the left-right direction.

The above suspension structure allows (i) the first buffer member 31 aand the upper surface of the unit frame 13 to come into contact witheach other and (ii) the lower surface of the second buffer member 32 aand the upper surface of the regulating wall 33 a of the regulating body33 to come into contact with each other if the left and right rearwheels 3 have become lifted greatly at the same time. This prevents theleft and right rear wheels 3 from disadvantageously reaching theirmechanical limits, and also reduces the shock of the contact as a resultof each buffer member being compressed.

As described above, the left and right axle cases 20 are of the rigidaxle type. Thus, if one of the left and right rear wheels 3 has beenlifted greatly, the corresponding buffer member comes into contact withits opposing surface to prevent the rear wheels 3 from disadvantageouslybeing moved beyond their mechanical limits, and is also compressed toreduce the shock.

Other Embodiments

The present invention may alternatively be arranged as below other thanthe embodiment described above. Any member below that is identical infunction to a particular member described for the above embodiment hasthe same reference sign as that particular member.

(a) The present invention is applicable to a work vehicle including (i)a vehicle body 1, (ii) left and right front wheels 2 at a front portionof the vehicle body 1, and (iii) left and right axle cases of a rigidaxle type that correspond respectively to the left and right frontwheels 2, the work vehicle further including a lateral rod 35 forregulating lateral displacement of the axle cases at the front portionof the vehicle body 1.

(b) The present invention is not limited to a work vehicle including (i)a vehicle body 1, (ii) left and right rear wheels 3 at a rear portion ofthe vehicle body 1, and (iii) axle cases 20 of a rigid axle type thatcorrespond respectively to the left and right rear wheels 3 as describedfor the above embodiment. A work vehicle including (i) a vehicle body 1,(ii) left and right front wheels 2 at a front portion of the vehiclebody 1, and (iii) left and right axle cases of a rigid axle type thatcorrespond respectively to the left and right front wheels 2 asdescribed for the other embodiment (a) may be configured such that thefirst projection overlaps with and lies over an axle case in a plan viewso that the axle case has an upper surface that serves as the firstopposing portion.

(c) The present invention is not limited to a work vehicle including (i)a vehicle body 1, (ii) left and right rear wheels 3 at a rear portion ofthe vehicle body 1, and (iii) axle cases 20 of a rigid axle type thatcorrespond respectively to the left and right rear wheels 3 as describedfor the above embodiment. A work vehicle including (i) a vehicle body 1,(ii) left and right front wheels 2 at a front portion of the vehiclebody 1, and (iii) left and right axle cases of a rigid axle type thatcorrespond respectively to the left and right front wheels 2 asdescribed for the other embodiment (a) may include a second projectionprojecting upward from the upper surface of an axle case.

The other embodiment (c) may include a bar-shaped member projectingdownward from a position on that portion of the body frames 11 which isat the front portion of the vehicle body 1, the position being above thesecond projection. With this configuration, the bar-shaped member has alower surface that serves as the second opposing portion.

The other embodiments (b) and (c) are configured such that if the leftand right axle cases have become lifted greatly, the first projectionand the second projection, each of which overlaps with an axle case in aplan view, receives a force caused by the axle cases being lifted. Thisconfiguration provides a great strength and saves space. The embodimentdescribed above, which is configured such that a force caused by theaxle cases being lifted is received by the unit frame 13 (frame body),regulates the lifting of the axle cases 20 with use of the unit frame13. The embodiment described above thus involves a unit frame 13 thathas a great strength.

In view of the other embodiments (b) and (c), the other embodiment (a)can be described in detail as including (i) a first projectionprojecting downward from the left or right one of the body frames 11(which are at a front portion of the vehicle body 1) toward the uppersurface of the left or right axle case, (ii) a second projectionprojecting upward from that position on the left or right axle casewhich is opposite to the first projection in the left-right direction,and (iii) a lateral rod 35 having a first end connected with the firstprojection and a second end connected with the second projection.

With the above configuration, the lateral rod 35, which is presentbetween the second projection (which is on one of the axle casescorresponding respectively to the left and right front wheels 2) and oneof the body frames 11, allows the left and right front wheels to bestrongly positioned in the lateral direction. The other embodiment (a)may further include (i) a buffer member on the lower surface of thefirst projection and (ii) another buffer member on the lower surface ofthe bar-shaped member (which is present immediately above the secondprojection). For instance, if the left and right front wheels 2 havebecome lifted greatly at the same time, (i) the buffer member on thelower surface of the first projection comes into contact with the uppersurface of the corresponding axle case, while (ii) the buffer member onthe lower surface of the bar-shaped member comes into contact with theupper surface of the second projection, thereby limiting the lift of theaxle cases.

The first projection and the second projection ideally overlap with theaxle cases in a plan view as in the other embodiments (b) and (c).However, the ideal arrangement is often difficult to achieve in view ofhow various devices for the vehicle body 1 are arranged. The leftsupport 31 (which is an example first projection) and the regulatingbody 33 (which is an example second projection) may be present, forinstance, rearward of the axle cases 20 as described for the embodimentdescribed above. The left support 31 (which is an example firstprojection) and the regulating body 33 (which is an example secondprojection) may alternatively be present forward of the axle cases 20.

The above arrangement is applicable to both the respective axle cases ofthe front wheels 2 and the respective axle cases of the rear wheels 3.Whichever the arrangement is applied to, the first projection and thesecond projection are each desirably present close to the correspondingaxle case in a plan view. Such an arrangement allows for a relativelyfree layout of members including the first projection and the secondprojection.

(d) The embodiment described above may alternatively be configured as anexample such that (i) the first buffer member 31 a may be present not onthe lower surface of the left support 31 (which is an example firstprojection) but on that portion of the upper surface of the unit frame13 which is located immediately below the left support 31 (that is, atthe position of the left opposing portion S1 illustrated in FIG. 5)and/or that (ii) the second buffer member 32 a may be present not on thelower surface of the right support 32 (which is an example bar-shapedmember) but on that portion of the upper surface of the regulating body33 (which is an example second projection) which is located immediatelybelow the right support 32.

The configuration of the other embodiment (d) is applicable also to awork vehicle including (i) a vehicle body 1, (ii) left and right frontwheels 2 at a front portion of the vehicle body 1, and (iii) left andright axle cases of a rigid axle type that correspond respectively tothe left and right front wheels 2. If even one of the left and rightwheels has become lifted greatly, the buffer members each perform itsbuffer function and prevent the left and right wheels fromdisadvantageously reaching their mechanical limits, similarly to theembodiment described above.

(e) The embodiment described above may alternatively be configured as anexample such that the right support 32 (which is an example bar-shapedmember) is absent and that the regulating body 33 (which is an examplesecond projection) has an extended length in the up-down direction andhas an upper surface on which the second buffer member 32 a is present.With this configuration of the other embodiment (e), if the rear wheels3 have become lifted greatly, the second buffer member 32 a on the uppersurface of the regulating body 33 comes into direct contact with thelower surface of the corresponding rear frame 11 c. This prevents therear wheels 3 from disadvantageously reaching their mechanical limits.

The other embodiment (e) may alternatively be configured as a variationsuch that the right support 32 is absent, that the regulating body 33has an extended length in the up-down direction, and that the secondbuffer member 32 a is present on the lower surface of the correspondingrear frame 11 c. The configuration of the other embodiment (e) isapplicable also to a work vehicle including (i) a vehicle body 1, (ii)left and right front wheels 2 at a front portion of the vehicle body 1,and (iii) left and right axle cases of a rigid axle type that correspondrespectively to the left and right front wheels 2.

(f) The embodiment described above may alternatively be configured as anexample such that the first projection (which corresponds to the leftsupport 31 for the embodiment described above) and the second projection(which corresponds to the regulating body 33 for the embodimentdescribed above) may be switched around in position in the left-rightdirection. With this configuration, the lateral rod 35 is oriented atsuch a position as to connect (i) the second projection at a leftportion of the vehicle body 1 with (ii) the first projection at a rightportion of the vehicle body 1.

(g) The embodiment described above may alternatively be configured as anexample such that the lower end of the left support 31 (which is anexample first projection) may be lower in position than the upper end ofthe regulating body 33 (which is an example second projection) with thelateral rod 35 oriented horizontally between the left support 31 and theregulating body 33.

With the above configuration of the other embodiment (g), not only thefirst buffer member 31 a and the second buffer member 32 a are presentat respective heights that are asymmetrical to each other with respectto the center of the vehicle body 1, but also the lateral rod 35 isoriented horizontally. This allows the lateral rod 35 to receive astrong force in both a compressing direction and a tensile direction.

(h) The left and right axle cases are each made of, for example, a castmetal to be integrated with each other, and a transmission case fortransmitting a driving force to the left and right axle cases isseparated from the axle cases. With this configuration, the frame body(which corresponds to the unit frame 13 for the embodiment describedabove) may be in the form of a bar oriented in the lateral direction ofthe vehicle body 1.

With the above configuration of the other embodiment (h), the firstprojection is present on a body frame 11, the second projection ispresent on a frame body in the form of a bar, and the lateral rod 35 isoriented at such a position as to connect the first projection with thesecond projection.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a work vehicle including left andright axle cases of a rigid axle type, the left and right axle casescoaxially supporting left and right axles for driving left and rightwheels, respectively.

REFERENCE SIGNS LIST

-   -   1 Vehicle body    -   2 Front wheel (wheel)    -   3 Rear wheel (wheel)    -   11 Body frame    -   13 Unit frame (frame body)    -   20 Axle case    -   21 Rear axle (axle)    -   28 Suspension mechanism    -   31 Left support (first projection)    -   31 a First buffer member    -   32 Right support (bar-shaped member)    -   32 a Second buffer member    -   33 Regulating body (second projection)    -   35 Lateral rod    -   S1 Left opposing portion (first opposing portion)    -   S2 Right opposing portion (second opposing portion)

The invention claimed is:
 1. A work vehicle, comprising: a left wheelprovided for a vehicle body; a right wheel provided for the vehiclebody; a body frame provided for the vehicle body; a left axle connectedwith the left wheel; a right axle connected with the right wheel; a leftaxle case and a right axle case, the left and right axle cases being ofa rigid axle type and supporting the left and right axles so that theleft and right axles are coaxial with respect to each other; a leftsuspension mechanism via which the body frame supports the left axlecase; a right suspension mechanism via which the body frame supports theright axle case; a first projection projecting downward from a left orright portion of the body frame; a second projection projecting upwardfrom that position on either (i) the left and right axle cases or (ii) aframe body integrated with the left and right axle cases which isopposite to the first projection in a left-right direction; a lateralrod having a first end connected with the first projection and a secondend connected with the second projection; a first opposing portion atthat portion of either the left and right axle cases or the frame bodywhich is located below the first projection; and a first buffer memberon either a lower surface of the first projection or the first opposingportion.
 2. The work vehicle according to claim 1, further comprising: asecond opposing portion at that portion of the body frame which islocated above the second projection; and a second buffer member oneither an upper surface of the second projection or the second opposingportion.
 3. The work vehicle according to claim 2, wherein the firstopposing portion is an upper surface of the frame body; and the firstbuffer member is present on the lower surface of the first projection;the second opposing portion is a lower surface of a bar-shaped memberprojecting downward from the body frame; and the second buffer member ispresent on the second opposing portion.
 4. The work vehicle according toclaim 2, wherein the first buffer member and the second buffer memberare present at respective heights that are asymmetrical to each other inthe left-right direction with respect to a center of the vehicle body asviewed in a front-rear direction.
 5. The work vehicle according to claim1, wherein the left and right wheels are rear wheels provided at a rearportion of the vehicle body.
 6. A work vehicle, comprising: a left wheelprovided for a vehicle body; a right wheel provided for the vehiclebody; a body frame provided for the vehicle body; a left axle connectedwith the left wheel; a right axle connected with the right wheel; a leftaxle case and a right axle case, the left and right axle cases being ofa rigid axle type and supporting the left and right axles so that theleft and right axles are coaxial with respect to each other; a leftsuspension mechanism via which the body frame supports the left axlecase; a right suspension mechanism via which the body frame supports theright axle case; a first projection projecting downward from a left orright portion of the body frame; a second projection projecting upwardfrom that position on either (i) the left and right axle cases or (ii) aframe body integrated with the left and right axle cases which isopposite to the first projection in a left-right direction; a lateralrod having a first end connected with the first projection and a secondend connected with the second projection; a second opposing portion atthat portion of the body frame which is located above the secondprojection; and a second buffer member on either an upper surface of thesecond projection or the second opposing portion.
 7. The work vehicleaccording to claim 6, wherein the left and right wheels are rear wheelsprovided at a rear portion of the vehicle body.